Aluminum Wiring in Residential Buildings

 We discovered that a house we recently assisted in purchasing for our son was built in 1975 with aluminum wiring.   I had heard over the years that aluminum wiring is not desirable, and finding it in a property we own caused me concern.  So I undertook a deep dive into the topic to find out more.

How do you know if your house has aluminum wiring?  We found out through our home inspection at the time of sale.  It listed the wiring as aluminum.  But if you already own the property, you can simply do a little detective work.   I took apart outlets and found some to have all aluminum wires, and some had a combination of copper and aluminum.  The outlet pictures here has a combination.  The two push connections in the back (white and black wires) are copper.   Where the bit of wire is showing, note the distinctive copper (orangish) color.  The wire with the screw-down connection is aluminum.  The silver color of the actual wire is the give-way.   Just remember: copper is orange,  aluminum is silver.

 Here are the wires after I disconnected them.  It is even clearer now which wires are aluminum and which are copper.

As our house shows, some circuits may be aluminum and some copper in the same house.  To find out for sure if and where a house has aluminum, every switch and outlet would have to be checked.  It is fairly safe to simply remove the cover on the subpanel and see if there is copper or aluminum on each circuit,  but even if it is all copper there could still be aluminum between a switch and an outlet - which is exactly what is shown here.

What is the problem with aluminum wiring?  On 220 circuits and large commercial circuits, there really isn't a problem and aluminum is still often used in those situations today.

The problem comes in on the 110 residential circuits.  The rate at which metals expand and contract are different, and copper and aluminum have drastically different rates.  This can lead to connections that loosen over time, and the loose connection can generate heat at a high rate with aluminum wires.  This heat can start fires that have led to loss of life in some cases.  In addition, aluminum corrodes when it comes in contact with certain types of metal which leads to even worse connections and more heat.

Aluminum wiring is typically more flexible yet more brittle than copper in my experience, and the brittleness can cause the wires to break, leaving another way that excess heat can be generated leading to fire.

Special attention has to be paid whereever the aluminum wire comes in contact with another metal.  On 110 circuits, the problem often lies at the switch or outlet.  Most switches and outlets are not made with metals that are compatible with aluminum wires.  You can buy special switches and outlets that are compatible with both copper and aluminum - they are marked CO/ALR.

However, it is easy to forget to use them.  It is better to be safe and not use aluminum wire at switches and outlets at all.   Again 220 circuits are not a problem because virtually all connectors on those circuits are compatible with aluminum - unlike 110 devices.

Also - aluminum was widely used on 110 circuits from 1965 until 1975.  Outside of that time frame, the use of aluminum 110 wiring dropped drastically.  1965-75 saw aluminum used because copper prices had skyrocketed due to the Vietnam War.  The construction industry was not aware of the problems with aluminum at that time, so it seemed to be a cost effective solution to the copper price problem.

From 1965 until 1972, aluminum wire was produced at grade AA-1350.  The termination failure problem with the AA-1350 grade wires was quickly discovered and new safer grades such as AA-8000 were manufactured after 1972.  I have read, however, that electricians were allowed to continue using AA-1350 after 1972 until they had depleted their stock, so even homes built after 1972 may have AA-1350.  Note that even the AA-8000 wires need the special CO/ALR outlets and switches.

I have read about studies that showed the AA-1350 wiring is 55 times more likely to catch fire than copper wiring.  I could not find an equivalent study for the AA-8000 wiring.  Additionally, wiring becomes more dangerous as it ages.  Homes built before 1975 are over 40 years old now.

What can be done to correct aluminum wiring?  Significant research has been done on aluminum wiring now, and much of this body of work can be found online.   A well-respected leader in this field of research is Jesse Aronstein and his papers from the 1980s until the last few years are excellent sources of information.   Additionally, the US Government distributes Publication 516 from the US Consumer Product Safety Commission (CPSC) which describes approved solutions for aluminum wiring, as well as the history of aluminum wiring and why it is a problem.

Publication 516 states there are only three approved methods for permanently repairing aluminum wiring.

Solution 1:  Replace aluminum wiring with copper wiring.
Obviously this solution permanently and completely fixes the situation!  Therefore, it is the perfect solution.  It is also expensive.   If it is feasible and within budget,  replace!

 Solution 2:  COPALUM Repairs.
The COPALUM (pronounced cop - a - loom) solution uses a copper pigtail that is crimped onto the aluminum wire so that every switch, outlet and junction box has copper wire for attaching.   This pigtail is attached with a special crimp device and is only available through one company.  The company that produces the COPALUM tool won't even sell it to electricians - electricians must rent the tool.  In addition, electricians must attend special COPALUM training and be licensed to use the tool.  The number of current licenses in the United States is low - I have heard numbers ranging from 25 to 100.  In addition,  the COPALUM repairs must be done at every switch, outlet and junction box.  The estimate I received in 2015 to have my home done with COPALUM was over $100 per switch, outlet and junction box.  In this photo, the red (copper) and black (aluminum) wires are joined with a COPALUM connection.  COPALUM has been used for several decades now and has a long track record as a permanent, reliable solution.

Solution 3: AlumiConn Repairs.
Since over 1 million homes in the United States have aging aluminum wiring and solutions 1 and 2 are pretty expensive,  a smart company called King Innovation developed AlumiConn connections and placed them on the market in 2006.  In 2007, the AlumiConn connectors completed independent testing by Jesse Aronstein (mentioned above) and was placed on the CPSC-approved list in 2011.

Aluminum wires are fed into two of the holes in the AlumiConn connector, and a copper pigtail wire is fed into the third hole.  The set screws have to be tightened a VERY SPECIFIC AMOUNT for the connection to be safe, and therefore should be tightened with a torque screwdriver.

AlumiConn connectors also contain dielectric silicone inhibitor to reduce corrosion and run abut 25 degrees cooler than other types of connections.

This can be a very cost effective solution that should be done by a qualified electrician experienced with aluminum wiring and AlumiConn connectors.  However, I notice that packages of 100 AlumiConn connectors are sold at a variety of stores including Home Depot.  I am assuming that not all of these are bought by electricians.

Finally, there are a few drawbacks to AlumiConn.  Since several of these little purple AlumiConn devices may need to be placed in each outlet or switch box,  there may not be enough room in the box.  This may require the purchase and installation of oversized boxes which will lead to extra expense and possibly sheetrock repair.  Second,  aluminum wiring will still be in the home and, with all the extra connections and potential wire bending to fit into the tighter space, there is risk that the aluminum will break.  Third,  this can also be an expensive solution.  While I read some electricians online saying they would install these for $30 per outlet, switch, or junction box the quotes I received in my local area were $130 per outlet, switch, or junction box.   At that price, it was not any cheaper than COPALUM.  Fourth, the track record of AlumiConn is much, much shorter than COPALUM.  AlumiConn has been on the market less than 10 years as of right now.

So...what did I do in my home?  After getting input and bids from several electricians, I found that aluminum in my house was limited to the 20 amp circuit in the kitchen and a few wires between switches and outlets.  The majority of wiring in my house was copper.  Since I have a single story house with a generous attic space, running new copper wire to replace the aluminum is fairly easy and therefore the bid to replace the wiring was cost-competitive with COPALUM and AlumiConn.  So I replaced the aluminum wiring and, while we were in there, replaced the subpanel, the circuit breakers, and wired new smoke detectors throughout the home.  I don't have to worry about aluminum wiring any more.

DISCLAIMER.  Please note that I am NOT an expert or an electrician, and you should research this topic on your own.    I may have accidently misquoted sources above and only YOU can guarantee the safety of your home.

Excellent sources of information:
#1: Inspectapedia:  http://inspectapedia.com/aluminum/Aluminum_Wiring_Repair_Methods.htm
#2: US Consumer Product Safety Commission Publication 516
#3: All Jesse Aronstein documents